1. Field of the Invention
The present invention relates to a control system for an internal combustion engine, and particularly, to a system for controlling an internal combustion engine according to a pressure in the cylinder detected by a cylinder pressure sensor.
2. Description of the Related Art
Japanese Patent Laid-open No. 2004-100566 (JP '566) discloses a fuel injection control apparatus in which the cylinder pressure (pressure in the combustion chamber) is detected by a cylinder pressure sensor. A fuel injection amount, a fuel injection timing, and the like, are controlled according to the detected cylinder pressure. According to the disclosed apparatus, the crank angle Cmax at which the cylinder pressure reaches the maximum value is detected, and the fuel injection timing is corrected so that the detected crank angle Cmax coincides with a target value which is previously set according to the engine operating condition.
If the internal combustion engine is a diesel engine, an actual ignition timing changes depending on the cetane number of the fuel being used, even if the fuel injection timing is the same. Therefore, the control used by the above-described conventional apparatus is effective when the combustion characteristic of the fuel changes.
In an engine having an exhaust gas recirculation mechanism, the combustion state of fuel in the combustion chamber changes due to execution of the exhaust gas recirculation. Therefore, it is desirable to control the amount of exhaust gases being recirculated according to the actual combustion state. However, such a situation is not taken into consideration by the above-described control apparatus.